If an OpenVDB grid has an 8x8x8 block with the same value, it is stored as a tile with a single value. Now iterate over the bounding box and copy the value to all voxels for this case. Fix #91174: Hollow emission artifacts Fix #124064: Hollow density artifacts Pull Request: https://projects.blender.org/blender/blender/pulls/139231
Mantaflow
Mantaflow is an open-source framework targeted at fluid simulation research in Computer Graphics. Its parallelized C++ solver core, python scene definition interface and plugin system allow for quickly prototyping and testing new algorithms.
In addition, it provides a toolbox of examples for deep learning experiments with fluids. E.g., it contains examples how to build convolutional neural network setups in conjunction with the tensorflow framework.
For more information on how to install, run and code with Mantaflow, please head over to our home page at http://mantaflow.com
Debugging
You could export openVDB volume into mantaflow, by running Blender with:
blender --debug-value 3001
And then select Domain -> Fluid -> Cache - > Advanced -> Export Mantaflow Script.